Free-Standing Flexible Composite Film That Is Transparent, Omnipohobic, and Resistant against Steel Wool Abrasion

Abstract

The encapsulating film of current foldable smartphone touchscreens consists of a flexible, colorless polyimide substrate, layered stepwise with a top hard coat, an antireflection coat, and last with an outermost antifingerprint layer. A flexible polymer substrate is essential to overcoming the inherent bendability limitations of the hard coat. This study explores a different approach to encapsulating film fabrication. This method involves the infusion of GPOSS (octakis(3-glycidyloxypropyl)silsesquioxane), GPOSS-FC6 (GPOSS with a perfluorinated hexyl group), and a cationic ring-opening initiator into electrospun nylon nanofiber mat pores and subsequently photocuring the GPOSS mixture to create a composite. The resulting film is transparent, omniphobic, and remarkably flexible. A 40 μm thick free-standing composite film alone can endure over 1000 bending cycles with a 1 mm radius without cracking. Additionally, it exhibits superior wear resistance by withstanding hundreds of steel wool abrasions, surpassing that of a cured neat F-GPOSS hard coating. This study highlights the remarkable reinforcing effect of electrospun nanofibers on hard materials, enhancing simultaneously the normally exclusive properties: flexibility and abrasion resistance. The reported material should find applications in various fields beyond foldable touchscreens.

Synthesis of Mixed Ladder-Like Polysilsesquioxanes by Copolymerization of 2-(3,4-Epoxycyclohexyl)ethyltrimethoxysilane and Dodecyltrimethoxysilane

“…The measured data are summarized in Table . The H values are of interest because a high H value, with some exceptions, normally translates directly into high wear resistance. ,,, An H / E value greater than 10% and W e greater than 60% have been previously cited as the criteria for a high- H material to possess flexibility. , …”